两株番茄细菌性斑点病拮抗放线菌的鉴定及功能基因筛查

Identification of Two Antagonistic Actinomycetes Against Tomato Bacterial Spot Disease and Screening of Their Functional Genes

本研究从分离自新疆巴里坤盐湖的放线菌中筛选到两株抗菌活性放线菌GWB1-7和ZW2-11,该菌株对番茄细菌性斑点病致病菌(丁香假单胞杆菌番茄致病变种,Pseudomonas syringae pv.tomato)具有显著的抗菌活性。采用平板对峙法对上述菌株进行菌株拮抗分析,并对其进行菌株形态观察、系统进化树分析及抗生素合成相关功能基因筛查。结果表明:放线菌GWB1-7和ZW2-11不仅对丁香假单胞杆菌番茄致病变种具有显著抗菌活性,而且对大肠杆菌(Escherichia coli)和金黄色葡萄球菌(Staphylococcus aureus)的拮抗作用明显;放线菌GWB1-7在进化关系上与拟诺卡氏菌属(Nocardiopsis)放线菌最相近,而放线菌ZW2-11同链霉菌属(Streptomyces)放线菌聚类在相同的分支;这两株菌均携带有Nrps和Aph基因,另外GWB1-7菌株中还含有I型Pks基因,而ZW2-11菌株还含有II型Pks基因。放线菌GWB1-7和ZW2-11的鉴定及抗生素合成相关功能基因的筛查,为后期分离这些菌株中的活性代谢产物奠定理论基础。

Two antibacterial actinomycetes GWB1-7 and ZW2-11 were screened out from actinomycetes isolates sourced from the Balikun salt lake in Xinjiang.These strains have significant antibacterial activity against the tomato bacterial spot disease pathogen(Pseudomonas syringae pv.tomato).Antibacterial activity of these strains were analyzed by the plate confrontation method.Morphology observation and phylogenetic tree analysis of these strains were carried out.The functional genes related to antibiotic synthesis were screened out from these strains.The results showed that actinomycetes GWB1-7 and ZW2-11 not only exhibited significant antibacterial activity against Pseudomonas syringae pv.tomato,but also displayed obvious antagonism against Escherichia coli and Staphylococcus aureus.The GWB1-7 had the closest genetic relationship with actinobacteria of the genus Nocardiopsis.The ZW2-11 was clustered on the same branch as the genus Streptomyces.These strains carried both nonribosomal peptide-pynthetase(Nrps)and aminoglycoside phosphotransferases(Aph)genes.In addition,GWB1-7 strain also contained the type I polyketidesynthase(Pks)gene,while ZW2-11 strain contained the type II Pks gene.Identification of actinomycetes GWB1-7 and ZW2-11,as well as the screening functional genes related to antibiotic synthesis from the two strains,will lay foundation for isolating their active metabolites from these strains.